This riddle is a cautionary tale for workaholics

There is no harm in going the extra mile at work. If you get yourself into your boss's good books, you might even be rewarded handsomely for the extra work you put in. 

But beware the dangers of overworking yourself... 

Working to the point of burning out might give you a temporary sense of achievement, but in the long run your workaholic ways could cost you your health - or something worse. 

For the poor man in this riddle, being hardworking ended being his downfall. Can you figure out how he managed to work himself to death?

A man is discovered dead sitting at his desk, alone in the locked office. He did not commit suicide and there were no weapons in the room. The only clue is a sealed envelope on the desk in front of him.

How did he die?

Hint: it was one of the objects on his desk, something that he used every day, that spelled the end for him. 

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